Avaliação da circulação feto-placentária pela dopplervelocimetria, na segunda metade da gestação, em cadelas de portes miniatura e pequeno

Abstract

FERNANDES, M. P. Assessment of feto-placental circulation by Doppler velocimetry, in the second half of pregnancy, in miniature and small bitches. 2024. 44p. Dissertation (Master in Animal Science in the Tropics) – School of Veterinary Medicine and Animal Science – Federal University of Bahia, 2024. In small animal veterinary clinics, neonatal mortality represents a great emotional and economic loss for dog owners and breeders, therefore, knowledge of the characteristics that precede birth is essential to avoid these losses. Among the possible monitoring tests at the end of pregnancy is the assessment of fetal vessel flow using Doppler ultrasound, called Doppler velocimetry. In bitches, the fetal vessel evaluated is the umbilical artery, and its flow corresponds to the feto placental circulation. This assessment is carried out by the Resistivity Index (RI) and Pulsatility Index (PI). In this species, Doppler velocimetry of the umbilical artery aims to detect fetal distress and determine the moment of birth. Doppler studies indicate that the animal's weight influences blood flow, in which different values have been found in the umbilical vessels during pregnancy in dogs with different breed sizes. No evaluations of IR and IP values of the umbilical artery were found in miniature and small pregnant dogs. Therefore, the objective of the present study was to determine, through Doppler ultrasonography, the RI and IP values of the umbilical artery, during the last three weeks of pregnancy in bitches of small and miniature breeds, evaluating possible influence of size breed and litter size, in addition to characterizing the values of these indices in the last hours before giving birth in the bitches under study. 17 bitches and a total of 122 fetuses were used. Of these 17 bitches, 12 were initially classified as belonging to the miniature size (<6 kg) and 5 as small dogs (6-10 kg). At this time, the IR and PI of the umbilical artery were evaluated in the 6th, 7th and 8th weeks of pregnancy. In the second part, the 17 bitches were classified as small (up to 10 kg) and the IR and IP were evaluated in the last hours of pregnancy. To evaluate differences between IR and IP values during weeks and hours, the one-way ANOVA test was performed, followed by the Tukey test. When evaluating the normality of the IR variable, a normal distribution, Shapiro-Wilk, was not found (p<0.05). To verify the influence of litter between weeks, the Kruskal-Wallis non parametric test was used and the influence of breed size was evaluated using the Mann-Whitney non-parametric test. The software used was SPSS version 13.1. The results demonstrated that the average RI and IP values, in each week, differed in relation to other studies. The size and litter did not influence the RI within each week, but they influenced the PI in the 6th week of 24 gestation. There was a decrease in IR in the last 48 hours before birth (p < 0.05), but there were no differences in PI during the last hours before birth (p>0.05). The wide range of mean RI and IP values in the last weeks of pregnancy demonstrates the need for a greater understanding of fetal vascular hemodynamics according to the physiological variations of pregnant females.